Fast thermal response mold

ABSTRACT

An improved apparatus and method for making a fast thermal response mold is disclosed. The apparatus has a plurality of rows with each row having a plurality of cavities. Each cavity in each particular row is interconnected by bores to allow a thermal medium to pass therebetween in a serpentine manner. Each cavity has a sleeve fixed therein and adapted to fit a mold. The sleeve eliminates the need for O-ring sealing means utilized in prior fast thermal response molds.

The present invention relates to molds and, in particular, relates tomolds for compression molding operations wherein a plurality of moldsare retained in a mold frame.

In the compression molding of items such as golf balls, the molding ofthe golf balls is accomplished in a mold assembly comprising a pair ofmold plates each of which comprises a plurality of individual molds ormold cups within a mold frame. The mold frame has openings for receivingthe individual molds. In this way individual molds can be replaced ifthey become damaged or worn out without replacing the entire assembly.

In the manufacture of golf balls by compression molding, preformed golfball cover half shells are placed about a core, the mold plates joinedto form the mold assembly and the cover shells and core subjected toheat and pressure in order to melt the cover stock so that it flowsevenly about the core. This molds the cover about the core. After thecover stock has been molded about the core, the mold is then preferablycooled so that it in turn cools the cover stock to solidify it beforethe mold is reopened.

In accordance with standard compression molding techniques used today inthe manufacture of golf balls, the mold frame, which houses a multiplenumber of molds, has one or more channels running between adjacent rowsof molds. Heating or cooling fluid, as required, is passed through thesechannels in serpentine fashion. This results in a change in thetemperature of the mold frame which in turn heats or cools theindividual molds to change temperature of the cover stock.

U.S. Pat. Nos. 4,508,309 and 4,558,499 teach an apparatus and method formaking a fast thermal response mold assembly where the mold cupsthemselves are in direct contact with the thermal fluid used to heat andcool the mold. It is thus unnecessary to heat and cool the entire frameto change the temperature of the molds. Although the inventions taughtby the '309 and '499 patents are considered a major breakthrough for thegolfing industry, such mold assemblies are subject to mechanicalproblems. For example, it has been discovered that in commercialpractice the O-ring which provides the seal between the mold assemblyand the mold half sometimes begins to leak very soon after installation.Generally, the thermal medium used to heat the mold is steam. Escapingsteam from these mold assemblies makes working around such assembliesdangerous and also requires frequent maintenance and downtime to installnew O-rings.

It has now been discovered that this leakage problem can be solved byplacing a thin, metal sleeve with good conductive capability inside thecavity of the mold frame to completely seal the cavity. It has beenfound that such a sleeve does not materially affect the thermal responseof the mold. Such a sleeve has been found to alleviate the leakageproblem by elimination of the O-rings.

These and other advantages of the present invention may be understoodwith reference to the drawings wherein:

FIG. 1 is a top view of a prior art mold frame;

FIG. 2 is a top view of a mold frame according to the present invention;and

FIG. 3 is a partial cross-sectional view through line 3--3 of FIG. 2illustrating the mold plates with molds in operational position.

Referring first to FIG. 1, there is shown a standard mold frame such asis used for the compression molding of golf balls. The frame 10 isprovided with a plurality of cavities 12 in which are secured standardgolf ball half molds (not shown). Between each row of cavities 12 in theframe 10 is a bore 14, 14a, 14b, 14c. Bores 14, 14a, 14b, 14c areinterconnected at the opposed ends of the frame by cross-bores 16, 16a.Each bore and cross-bore is respectively plugged at each end by a shortthreaded plug 18.

A thermal medium such as steam, or cooling liquid, such as water,introduced through coupling 20 and withdrawn through a similar coupling(not shown), is passed through the bores 14, 14a, 14b, 14c in order toheat or cool the individual molds as desired. In order to have the flowof the thermal medium follow a serpentine series path through the moldframe, the cross-bores 16, 16a are selectively blocked by a plurality oflonger threaded plugs 22 inserted into the cross-bores alternatelybetween adjacent bores 14, 14a, 14b, 14c on the opposed sides as shownin FIG. 1.

In order to heat or cool the mold disposed in each individual cavity 12,it is necessary to heat or cool the mass of metal in the mold framebetween the cavities 12 to the temperature of the thermal medium passingthrough the mold frame 10.

In FIG. 2, a mold frame according to the invention is shown generally at24. A plurality of cavities 26 for accommodating golf ball half molds(not shown) are disposed in a mold frame plate member 28. The molds arepreferably in a closely packed arrangement. A closely packed arrangementis defined herein as one in which the distance between lines connectingthe centers of the cavities in each row is less than 2 times the radiusof the cavities. It is preferred that the spacing between rows ofcavities be in the range of about 1.25 to about 1.375 times the radiusof the cavities. It will be appreciated that other arrangements may beutilized, but the arrangement illustrated is preferred in order to takeadvantage of the fact that less space is required in a mold frame inaccordance with the invention. The closely packed arrangement enables anincreased number of balls to be molded in a press and mold ofpredetermined size, thus increasing productivity and reducing energyconsumption. Preferably, 63 cavities replace the 42 cavities in aconventional mold. In such an arrangement there are suitably nine rows,each of which has seven cavities.

A plurality of bores 30, 32, 34, 36, 38, 40, 42 penetrate respectivelythrough each row of cavities 26, thus forming channels for providingfluid communication between each adjacent cavity 26 in the row. It willbe appreciated that other interconnections may be incorporated; however,the serial interconnection is preferred. Bores 30 through 42 areinterconnected at the opposed ends of mold frame 28 by cross-bores 44and 46.

An inlet 48 for receiving fluid is disposed at one end of bore 30 and anoutlet 50 is disposed at the end of bore 42 on the opposite side frominlet 48. The remaining ends of each bore and cross-bore arerespectively plugged by a plurality of short plugs 52 threadinglyreceived therein. It will be appreciated that other means such asexpansion plugs may be utilized for the purpose of sealing the ends ofthe bores.

Longer plugs 54 disposed alternately between adjacent bores on oppositesides of the plate serve to selectively block the cross-bores to createa serpentine series flow of the thermal medium through the adjacentcavities. It will be appreciated that other means such as a force fitplug may also be used to block fluid flow through the cross-bores ifdesired. In accordance with the present invention, a fluid tight sleeve58 is affixed in each cavity 26. The sleeve is preferably molded to theperimeter 60 of the cavity but may be affixed by any means which makesit fluid tight.

FIG. 3 is a partial cross-section of a pair of mold plates having thehalf molds therein and in abutting engagement in the operationalposition for molding golf balls taken along the line 3--3 of FIG. 2.Since the plates are substantially identical, the reference numbers inthe figure are identical for each.

As shown in FIG. 3, the mold frames 28 are held in opposing abutmentduring the molding operation. Half molds 56 are disposed in the cavities26 of frames 28 to be held in opposed engaging abutment. A sleeve 58 isaffixed to each cavity 26. The sleeve 58 may be fixed in cavity 26 bywelding or soldering sleeve 58 to frame 28, but more preferably sleeve58 is brazed to frame 28. Nickel and silver alloys are the preferredsolder in brazing sleeve 58 to frame 28.

The mold frames 28 are then mated and indexed. Next, the sleeves 58 ofboth the upper and lower mold frames are machined so that sleeves 58will receive opposing half molds 56 in proper alignment and registrationwith respect to each other. The sleeve 58 should be of such dimensionthat half mold 56 must be press fit therein, thus providing good thermalconductivity. The sleeve 58 is attached to the inside cavity 26 suchthat cavity 26 becomes leakproof to the fluids in bores 32-42. It ispreferred that sleeve 58 is made from the same material as the frame. Asuitable material is free machining steel or 410 stainless steel. Thepreferred final thickness of the sleeve is 0.08 to 0.1 inches. Thisallows for good thermal conductivity between the fluids and mold 56while still maintaining good structural integrity.

It will be appreciated, especially from FIG. 3, that with sleeve 58fixed in cavity 26, the thermal medium flows around sleeve 58 throughchannels 59. The fluid path within the mold frame 28 is thus sealed, andthere is no need for O-rings or other sealing means between the molds 56and the frames 28.

If desired, a boss 70 in the lip 66 may be included for keying the halfmolds into the mold frame in known manner. Further, registration pins 72or mounting lugs 74 may be utilized in one frame as shown in FIG. 2 withcorresponding holes or lugs (not shown) in the other frame.

The half molds 56 according to the invention are preferably made ofbrass or other high heat-conductivity metal so that the mold temperaturemay quickly come into equilibrium with the temperature of the thermalmedium itself without the necessity for the lag time required for themold frame itself to achieve the desired temperature.

It will be understood that the claims are intended to cover all changesand modifications of the preferred embodiments of the invention hereinchosen for the purpose of illustration which do not constitutedepartures from the spirit and scope of the invention.

What is claimed is:
 1. A mold frame for receiving a plurality of halfmolds comprising:(a) a frame plate member, said plate member having aplurality of rows of cavities therein; (b) a fluid-tight sleeve fixedwithin each said cavity to said frame plate member by means of solderingor brazing, said sleeve being suited for receiving a replaceable halfmold therein; (c) a fluid passage being defined between the walls ofeach said cavity and each of said sleeve; and (d) fluid communicationmeans interconnecting the fluid passages of adjacent cavities.
 2. In amold frame suitable for receiving a plurality of half molds wherein aframe plate member defines a plurality of cavities and boresinterconnecting said cavities to provide serpentine fluid communicationsbetween each cavity, the improvement comprising a sleeve fixed in eachsaid cavity to said frame plate member to produce a fluid-tight sealbetween said frame plate and said sleeve, said sleeve defining a spacebetween said sleeve and the walls of said cavity, said space providingmeans by which said fluid flows around said cavity, and said sleevebeing suitable to receive said half molds.
 3. The mold frame of claim 2wherein said cavities are arranged in a plurality of rows.
 4. The moldframe of claim 2 wherein the sleeve is made from stainless steel.
 5. Themold frame of claim 2 wherein the sleeve is about 0.08 to about 0.1inches thick.
 6. A mold plate comprising:(a) a frame plate member; (b)said plate member having a plurality of cavities therein; (c) aplurality of replaceable half molds; (d) a sleeve fixed within each saidcavity to said frame plate member to provide a fluid-tight seal betweensaid mold frame member and said sleeve, said sleeve defining a spacebetween said sleeve and the walls of said cavity, said sleeve beingsuitable for receiving said replaceable half molds; and (e) meansoperative to provide serpentine fluid communication between saidcavities.
 7. The mold frame of claim 6 wherein said plate member boresinterconnect the plurality of cavities.